Three-dimensional imagery can be synthesized using polarization control following the projector and also employing polarization controlling eyewear, as generally discussed in U.S. Pat. No. 4,792,850 entitled “Method and system employing a push-pull liquid crystal modulator” filed Nov. 25, 1987, and in U.S. Pat. No. 7,905,602 entitled “Polarization conversion system for stereoscopic projection” filed Sep. 28, 2007, both of which are herein incorporated by reference in their entireties.
A conventional implementation of polarization control at the projector is shown in FIG. 1. In this implementation, nearly parallel rays emerge from the output of the lens 10, appearing to originate from a pupil 12 inside of the lens 10, and converge to form spots on a screen 14. Ray bundles A, B, and C in FIG. 1 are bundles forming spots at the bottom, center, and top of a screen 14, respectively. The light 20 emerging from the projection lens is randomly polarized, depicted in FIG. 1 as both s- and p-polarized light (s-polarized light is conventionally represented as ‘o’; p-polarized light is represented with a double arrow-ended line). The light 20 passes through a linear polarizer 22, resulting in a single polarization state after the polarizer 22. The orthogonal polarization state is absorbed (or reflected), and the light flux after the polarizer 22 is typically less than half of the original flux, thus resulting in a dimmer final image. The polarization switch 30 is synchronized with the image frame, and the polarization state 24 emerging from the polarization switch is alternated, producing images of alternately orthogonal polarization at the screen. Polarization-selective eyewear allows images of one polarization to pass to the left eye, and images of the orthogonal polarization to pass to the right eye. By presenting different images to each eye, 3D imagery can be synthesized.
This conventional system has been used in theaters. However, the conventional system requires that greater than 50% of the light is absorbed by the polarizer, and the resulting image is greater than 50% dimmer than that of a typical 2D theater. The dimmer image may limit the size of theater used for 3D applications and/or may provide a less desirable viewing experience for the audience.